1. Field of the Invention
The present invention refers generally to the winding of a filament onto a bobbin or canister, and, more particularly, to controlling the winding of such a filament to a high degree of accuracy without physically contacting the filament for this purpose.
2. Description of Related Art
There are many situations in which a filament is wound onto a bobbin or canister in an even and consistent winding and where inconsistencies such as gapping or climb-back are cause for rejection. An example is when an optical fiber or metal wire filament is wound onto a canister for subsequent dispensing during flight of a vehicle to maintain a data link with launch site equipment. When used for this purpose, an improperly wound bobbin or canister may produce stress in the filament during dispense that can cause it to break upon use, or, if not that, stress to the point that transmission of data will be less efficient.
Known current systems for controlling winding precision rely upon open loop control and do not monitor the actual filament position as it is applied to a bobbin or after it has already been laid down on the bobbin. In accordance with these known techniques, the filament is wound by traversing the canister to pre-programmed locations and it is merely assumed or expected that the filament will fall into proper position. It is known that variations in the angle that the filament makes on approaching the canister during winding, the filament diameter, as well as tension and surface finish of the filament may easily result in the filament being improperly placed on the bobbin and ending up with a defective wind which must be removed or rewound. All of this increases possibility of filament stress, contamination and increased winding time. Where such a bobbin is to be used for data link on a missile, for example, if the filament is caused to break because of defective winding, the missile may be unable to locate its target.